The primary purpose of the newly established Transgenic Mouse Shared Resource is to provide an efficient and economical means for producing genetically engineered mice for members of the Massey Cancer Center. Over the past 10 to 15 years, transgenic and "knock-out" mice have become an indispensable tool in cancer research. The utility of such models ranges from studies of the basic biology of tumorigenesis and progression to the creation of genetically accurate tumor models for evaluating novel therapeutic approaches. The Transgenic Mouse Shared Resource will greatly facilitate the development and utilization of new mouse models for cancer by Massey Cancer Center investigators. Specific services provided by this Shared Resource include: 1) Transgenic mouse production. The core will generate at least three transgenic founder mice for each transgene. 2) Knock-out mouse production. The core can perform all or a subset of the following procedures: ES cell electroporation; ES cell culture under appropriate selection conditions; expansion of drug-resistant clones; Southern/PCR screening of clones for he correct recombination event; and injection of targeted ES cells into blastocysts for chimeric mouse production. 3) Mouse line rederivation. Lines of pathogen-infected mice will be rederived by embryo transfer to generate pathogen-free lines. 4) cre line X indicator line interbreeding. Liens of cre-expressing transgenic mice will be interbred to a core-maintained indicator line of mice (129-Gtrosa26/tm1/Sor) to permit characterization of cre expression. 5) Consulting/support services. The core provides consultation on general transgenic/knock-out approaches and on vector design and offers protocols and demonstrations of basic mouse husbandry techniques, including breeding strategies, weaning, ear punching and tail DNA isolation. 6) Embryo cryopreservation. In the second year of this funding period, the core will add embryo cryopreservation as a service, as a means of preserving lines of mice without active breeding and to safeguard against the loss of breeding lines due to disease.